Current through Reg. 50, No. 187; September 24, 2024
(1)
In the construction of a well, reasonable caution shall be taken to maintain
the work site so as to minimize the entrance of contaminants into the water
resource. Materials used in construction shall be reasonably free of
contamination. The requirements for construction of public supply wells can be
found in Chapter 62-555, F.A.C.
(a) During
construction, the water used to mix the drilling fluids must either maintain a
minimum free chlorine residual of 10 mg/l or be supplied from a potable well or
water supply. If the well or water supply is a known source of contamination or
is within a known area of contamination, it shall not be used to provide water
to construct the well.
(b)
Disinfection of filter or gravel pack materials will follow guidelines found in
AWWA Standard A100-84, Section 11.4, unless materials are obtained from a
commercial source.
(c) Upon
completion of construction, the well must be disinfected using a solution of
water and available chlorine compounds providing a concentration not less than
50 mg/l. USEPA Manual of Well Construction Practices, EPA-570/9-75-001, Section
54.001-000-000, provides a tabular determination of disinfectant per 100 feet
of well depth to achieve the required residual.
(d) For non-potable (non-domestic) wells the
contractor may elect either to maintain a minimum of 10 mg/l free chlorine in
the water used to mix the drilling fluid during construction of the well or to
disinfect the completed well with a solution of water and available chlorine
compounds at a concentration of no less than 50 mg/l. Development should occur
prior to disinfection so the well may be cleared of chlorine by flushing the
entire water system prior to use. The disinfecting agent shall be left in the
well for a period of at least twelve hours and then pumped to clear the
disinfecting agent taking care to minimize potential damage to the environment.
Free-flowing artesian wells will be disinfected by using either potable water
or maintaining a minimum free chlorine residual of 10 mg/l in water used to mix
the drilling fluid until the free flowing water zone is
reached.
(2) For wells
which penetrate multiple aquifers or water bearing zones the well shall be
completed so as to prevent cross-contamination. If significantly different
water quality exists between these aquifers or water bearing zones, leakage of
water from one aquifer or water bearing zone to another must be
prevented.
(3) For wells finished
into unconsolidated aquifers, continuous casing shall extend from the well's
terminus to the well screen. The well screen shall be attached to the casing
with a watertight seal. The lower terminus of the well screen shall be sealed
to prevent the entrance of particulate materials. A tailpipe is allowed if
affixed to the screen with a watertight seal and plugged at its lower
terminus.
(4) For wells completed
into consolidated aquifers, a continuous casing shall extend from the upper
terminus and be seated into:
(a) The producing
aquifer, or
(b) Into a consolidated
stratum within a continuous non-caving confining unit immediately overlying the
aquifer from which the water is to be withdrawn.
(5) For wells completed into consolidated
aquifers which are constructed using telescoping casings the following
practices will be acceptable:
(a) Two casings
may be telescoped and sealed with a packer and one casing centralizer when
paragraph 40C-3.517(4)(c),
F.A.C., construction methods are used. Two centralizers shall be used when the
internal casing is grouted. A minimum of 5 feet overlap is required for
nonpublic supply wells which are less than 6'' in diameter. A minimum ten feet
of overlap is required for nonpublic supply wells a minimum of 6'' or more in
diameter. The minimum required overlap for public supply wells remains 20 feet,
as set forth in Chapter 62-555, F.A.C.
(b) The annular space between telescoped
casings shall meet minimum grouting standards in subsections
40C-3.517(2) and
(3), F.A.C.
(6) The upper terminus of the well to which
the well head is affixed shall extend either to land surface or to finished
grade, whichever is higher, or where a potential physical or traffic hazard
exists, the well head must:
(a) Be placed in
an appropriate enclosure terminating at land surface or finished grade,
whichever is higher, that allows vertical access to the casing and proper
drainage, and that protects the well head from the entrance of
contaminants;
(b) Be completed to a
point 18 inches or less below land surface or finished grade, whichever is
higher. There must be a concrete marker 10 inches in diameter and 4 inches
thick with an inserted metal disk clearly marked as required in subsection
40C-3.461(2),
F.A.C., placed at land surface or finished grade. The upper terminus of the
casing shall be sealed in a manner which prevents the entrance of contaminants
into the well; or
(c) Be completed
to a point 18 inches or less below land surface or finished grade, whichever is
higher. A tee and nipple must be affixed so that the casing extends to land
surface or finished grade while permitting a below grade water line to extend
to a designated location remote to the water well. This subsection does not
apply to public supply wells regulated under Chapter 62-555,
F.A.C.
(7) For wells
constructed in those areas of the District in which chert occurs, the well
casing shall extend from its upper terminus to:
(a) A point below the dry season water level
of the producing aquifer, or
(b) A
point firmly seated in chert overlying a stratum of limestone if the underlying
limestone does not produce a quantity of particulate materials after
development that will clog a filter or decrease the ability of the well to
produce water.
(8) Water
wells constructed using Bentonite grouts shall meet all the following
requirements:
(a) The casing seat must be
clean allowing the casing to set at the total depth bored in a hole reasonably
free of drill cuttings;
(b) A
formation boot or Portland Cement plug must be installed at the casing
seat;
(c) Portland Cement must be
placed in the upper three feet of the annular space to prevent deterioration of
or damage to the Bentonite seal; and
(d) Bentonite grout may be used only on
domestic, irrigation, water source or ground source heat pump installations or
well abandonments with a nominal casing diameter of four inches or less. Use of
Bentonite grout is not allowed on public supply wells or where artesian flow
occurs or in any identified contamination sites.
In all circumstances the requirements of subsection
40C-3.512(2),
F.A.C., must be met. All caving zones within the well must be cased or lined
when caving occurs below the casing seat. No casing may be seated into an
unconsolidated unit above the producing aquifer.
(9) In addition to the other applicable
standards contained in this chapter, wells constructed in the Picketville
Landfill Special Construction Criteria Area shall meet the following minimum
criteria:
(a) For Zone A, of new wells which
are completed into the surficial aquifer system, including the upper sand and
lower shallow-rock zone, to a depth of 110 feet below land surface or less than
five feet into the intermediate aquifer system are prohibited. This prohibition
of new wells does not apply to moniter wells, recovery wells or piezometers
which may be used for assessment of clean up of contamination sites.
(b) New wells may be completed into the
intermediate aquifer system producing zone at least 300' below ground surface,
or into the Floridan aquifer system.
(c) New wells penetrating the intermediate
system or Floridan aquifer producing zones shall be constructed in the
following manner:
1. A minimum 6-inch exterior
casing shall be installed and grouted to no less than five feet into the top of
the confining unit immediately below the shallow rock zone of the surficial
aquifer system.
2. A minimum 2-inch
interior casing within the 6-inch casing shall be installed and grouted to the
producing zone. For wells constructed into the intermediate system, the
intermediate aquifer shall be screened unless the entire producing zone is
consolidated.
3. The top casing
diameters shall allow a minimum nominal grouting annulus of two
inches.
4. For telescoped wells
constructed in reliance on the criteria of paragraph
40C-3.517(4)(c),
F.A.C., in addition to the overlap created by the telescope, a fifty foot
minimum length of internal casing shall be grouted below the telescoped
joint.
5. The internal casing of
all wells shall be completed to a minimum of twelve inches above
grade.
(d) In Zone A,
each existing well in the surficial aquifer system shall be abandoned when
public supply lines are installed adjacent to the property served by the
well.
(e) All Chapter 62-524,
F.A.C., construction standards shall be met in both Zone A and Zone
B.
(10) In addition to
the other applicable standards contained in this chapter, wells constructed in
the Fairbanks Special Construction Criteria Area shall meet the following
minimum criteria:
(a) In Zone A, new wells
which are completed into the Surficial Aquifer System or into the Intermediate
Aquifer System, are prohibited. This prohibition of new wells does not apply to
monitor wells, recovery wells or piezometers which may be used for assessment
or cleanup of contaminated sites.
(b) In Zone A, new wells penetrating the
Floridan Aquifer producing zones must be constructed in the following manner:
1. A minimum 12-inch exterior casing shall be
installed and grouted to no less than five feet into the upper confining unit
of the intermediate aquifer system.
2. A minimum 8-inch interior casing within
the 12-inch casing shall be installed and grouted to no less than five feet
into the lower confining unit of the Intermediate Aquifer System.
3. A maximum 4-inch permanent water bearing
casing within the 8-inch casing must be installed into the Floridan Aquifer
System to a depth of at least one full casing lengths below the formation
contact.
4. The casing diameters
shall allow a minimum nominal grouting annulus of two inches.
5. The internal casing of all wells shall be
completed to a minimum of twelve inches above grade.
6. In Zone A, all new wells shall be logged
using gamma, caliper or video equipment.
(c) In Zone A, each existing well in the
Surficial and Intermediate Aquifer System shall be abandoned when public supply
lines are installed adjacent to the property served by the well.
(d) In Zone A, water quality samples must be
taken and analyzed by Environmental Protection Agency methods 601, 602 and 610
where the casing is set in the Floridan Aquifer System. Water quality results
from the Floridan Aquifer System shall reveal no contaminants before well
construction is completed. In the event that water quality testing indicates
that there is contamination in the groundwater, the well shall be plugged and
abandoned pursuant to Chapter 40C-3, F.A.C.
(e) In Zone B, new wells shall be logged,
sampled and analyzed by Environmental Protection Agency methods 601, 602 and
610 for groundwater contaminants.
(f) Prior to any well construction in the
Fairbanks Special Construction Criteria Area identified in subsection
40C-3.502(3),
F.A.C., all persons shall obtain a well construction permit from the St. Johns
River Water Management District. Construction standards as provided in Chapter
62-524, F.A.C., shall be applicable to all well construction in the Fairbanks
Special Construction Criteria Area.
(g) In Zone A and Zone B, all unused wells
must be capped and locked or plugged and abandoned. In Zone A, wells connecting
separate aquifer systems must be plugged and
abandoned.
Rulemaking Authority
373.044,
373.113,
373.309 FS. Law Implemented
373.103(1),
373.306,
373.308
FS.
New 10-14-84, Amended 4-23-85, Formerly 40C-3.512,
40C-3.0512, Amended 9-17-89, 9-16-93, 8-30-94,
3-5-95.
